PAS not working? EDIT: SOLVED!

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studio45uk

100 µW
Joined
Oct 14, 2021
Messages
7
Hi guys, new to the forum, thankful for any help you might be able to give :)

I'm trying to fix a BH Bikes Emotion that had unrecoverable error 13. I have replaced all the electronics with generic components from eBay, as there were no spares available from BH Bikes on any website I could find. I bought an S866 display with "20A" no-name controller together as a kit, and installed those. At this point I discovered that the bike does not have a PAS, but rather a torque sensor in the rear mech hanger. The generic controller does not have an input for this signal - hooking it up to the PAS input just gives an error - so I bought an S-V12 PAS and connected that up.

I can get the motor to spin to full speed using a thumb throttle, and it also work correctly in walk mode. However, I can not get PAS to work properly at all. The best I have achieved is brief pulses of power when rotating the cranks *very* slowly. This is with PAS sensitivity set to 1 and PAS level set to 5. Any other setting produces no motor output at all at any crank speed, and moving the cranks at any normal speed produces no motor output with any settings. The red light on the sensor flashes correctly 12 times per revolution and the controller is set for a 12 magnet sensor. Driving mode is set to "PAS and throttle".

Since these are all brand new parts I'm not expecting anything to have a fault, but I can not work out what the heck is going on. Has anyone got a bright idea?

Thanks in advance, Matt ;)
 
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Update: Checked the supply voltage to the PAS and it was 4.28v, thought that might be the problem so spliced in a good 5.02v wire from the throttle connector - still no joy...PAS is putting out correct +5v pulses...Controller must be at fault I guess, just not reading the pulses correctly? Damn annoying to get a lemon!
 
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I've been having the same problem with several bikes I've been working on. I've used new sensors, new controller. Tried pedaling both directions, checked the voltage and voltage pulses. Everything checks out but it still doesn't function.
 
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I'm really hoping to find a solution that gets the pedal assist working. I don't give two hoots about pedal assist, but many people want it working. I'd like to solve this puzzle
 
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Digger101 said:
I'm really hoping to find a solution that gets the pedal assist working. I don't give two hoots about pedal assist, but many people want it working. I'd like to solve this puzzle
Click to expand...

Just based on observation, hoping doesn't usually produce many solutions with ebikes. Even praying rarely works.
 
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Digger101 said:
I'm really hoping to find a solution that gets the pedal assist working. I don't give two hoots about pedal assist, but many people want it working. I'd like to solve this puzzle
Click to expand...

only real way to solve this is to have a known good working one and try it on the controller. if it work's, it's the PAS Magnets, if it doesn't, it's the controller.

if you don't have a known good working one and if the controller is programable, might be something in the settings. heck even if it's not programable, it still might be something in the settings that is locked.

good luck!
 
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Update: After another whole day of p*ssing abaht I have discovered the problem...I think.
SO I bought another generic controller to see if that would work. It took ages to arrive, and when I have it wired up, works even less well than the last one - won't talk to the display at all; and for some reason my display has P20 locked out, not able to be adjusted, so I can't change its communication protocol. FML.
So I hooked up the first controller again to see if that would unlock P20. No dice. Still only works in walk mode or by the thumb throttle. So I decided to take a risk and start tapping the blue PAS wire onto 5v and GND wires in case the sensor was faulty after all. MANAGED TO GET IT TURNING!
It seems the controller is expecting negative pulses ie the blue PAS wire to be pulled up to 5v normally, and grounded when a magnet passes. If I tap the blue wire onto the black wire repeatedly I get motor action that seems to correspond to how fast I'm tapping.
SO the solution is a different sensor, or a 1-transistor logic inverter deadbugged in there somewhere.

Does anyone know a reliable source for negative-output PAS sensors? None of the eBay or Amazon listings really seem to specify what the polarity is...

thanks
Matt
 
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It's this one https://www.ebay.co.uk/itm/294312417011
s-l1600.jpg
 
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The more I think about this, the more confused I get. I'm not sure what I wrote above makes sense. Since the signal's not actually going negative - ie *below* ground - surely any square wave should work? If the controller wants to start counting pulses from the first *falling* edge, it'll just miss out the first one, and then count as normal right?
Gonna try the logic inverter today anyway and see if she chooches...
 
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Well, it works with the inverter installed! Still not sure it's logical but what the hell...
So I used a BC237 transistor, 100k pull up to 5v on the collector, 1k base resistor, emitter to ground. Signal goes in thru the 1k and comes out inverted at the collector. Wrapped it up in heatshrink and stuffed it in the frame. Now get correct response to pedalling from the controller.
Hope this is helpful to someone else :)
 
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